Piping 2 grep commands into wc

one of these lines has both, but I want lines with only 'Rake'. I have tried

grep Rake a.txt | grep -v rake a.txt | wc

returns 90 lines?

I want to find all 3 lines with Rake, pipe it into grep, find if any of those 3 lines include Rake but not rake, and then use wc to count the lines that do. I could use redirect to make another file and then grep -v that new file, but that's not really my goal here. I'm sure it's something simple, but how do I fix my command?